Photographic emulsions containing colloidal material and alkylene oxide polymers



A. H. HERZ Nov. 6, 1962 PHOTOGRAPHIC EMULSIONS CONTAINING COLLOIDAL MATERIAL AND ALKYLENE OX'IDE POLYMERS Filed April 18, 1960 Ari/:urli Herz IN V EN T06. BY MM ATTORNEYS A LIS'NSG United States This invention relates to photographic emulsions and particularly to a method for increasing the speed and contrast of such emulsions.

It is well known that silver halide emulsions may be chemically sensitized with a variety of materials so as to increase the speed and generally the gamma or contrast of the emulsions as opposed to optical sensitizing in which the spectral range of sensitivity is increased. Chemical sensitization usually results either from the formation of silver sulfide on the surface of the silver halide crystals, thus increasing sensitivity, or from the formation of small amounts of silver from the reduction of silver halide. Either of these methods of sensitization requires that -the silver halide enter into chemical combination with the compound which imparts the sensitizing effect. Some classes of compounds, such as certain ethylene oxide condensation products and certain cationic surface-active salts increase sensitivity of silver halides without apparently entering into chemical combination with the silver halide. It is the sensitization of this latter type with which the present invention is primarily concerned.

Accordingly, it is the object of the present invention to provide new photographic emulsions which are capable of exhibiting improved speed and contrast characteristics. It is a further object to provide a process for preparing such emulsions. Another object is to use certain new combinations having a synergistic effect despite the face that one component of the combination would be exepected to actually be deleterious.

These and other objects are attained in accordance with this invention wherein the speed and contrast of silver halide emulsions are increased using certain water insoluble colloidal metals and metal sullides as defined hereinafter in combination with an alkylene oxide polymer, preferably a polyethylene oxide. The combinations embodying the invention exhibit a synergistic eifect in that the increase in speed and contrast is beyond the total effect obtained by the use of the individual constituents of the combination alone. In this connection the unexpected synergistic interaction of the polyethylene oxides with the colloidal particles per se was noted to be enhanced in the presence of a small amount of iodide present in the developer if it was not already present in the emulsion. ln accordance with the invention, water-insoluble colloidal metals and water-insoluble metal suldes are incorporated in a silver halide emulsion such as a silver bromoiodide emulsion to which a polyethylene oxide has been added. The synergistic increase in contrast and speed is obtained upon development in the presence of a conventional photographic developer. Normally, the individual constituents of the invention are incorporated into the emulsion prior to the coating of lthe emulsion on a support; however, equal results are obtained where the ethtylene oxide polymer is added to the developer.

As pertains to the sensitizing combination of this invention, it was particularly unexpected to observe a synergistic effect resulting from combination of the water-insoluble metals and metal suldes of this invention with the ethylene oxide polymers since it is known that the addition of certain colloidal metals, such as metallic silver, to an emulsion often results in substantial speed losses due i arent to the absorption of light by the colloidal material. I have now found that the combination of colloidal metals, colloidal silver for example, with an ethylene oxide polymer resulted in speed gains, particularly on prolonged `development, which not only overcame the initial speed losses due to the absorption of light by the colloidal silver but which were several times greater than that obtainable by the use of the ethylene oxide polymer alone. Thus, whereas a polyethylene oxide increased the speed of a silver halide emulsion by a factor of not more than two, an approximately tenfold speed gain was achieved in a silver bromoiodide emulsion by the combination of colloidal silver with the same polyethylene oxide and this was accompanied by a pronounced increase in contrast. The increase in contrast and speed obtained according to this invention was found also to occur in the presence or absence of optical sensitizing dyes. It was found also that any of Vthe standard black-and-White or color emul, sions can be used in the practice of this invention.

The process of this invention can be carried out using colloidal metals such as colloidal silver, gold, platinum, palladium, and colloidal metal sulfides such as silver sultide and zinc sulfide. The amount of colloidal material can vary considerably. Advantageously, the amount of colloidal material can vary from about 0.001 to about 3.0 grams per mole of silver halide with the range of from about 0.5 to about 1.5 grams per mole of silver halide being especially useful.

The concentration of polyethylene oxide polymer can also vary, for example, from about 0.25 to about 5.0 grams per mole of silver halide. Optimum concentration of polyethylene oxide polymer in the emulsion is from about 1.2 to about 5.0 grams per mole of silver halide. The invention is also operative when the ethylene oxide polymer is added to the developer in the range from about 0.05 to about 5 .0 grams per liter of developer.

In the process of -this invention, it was found that the synergistic effect was enhanced where iodide was present in the system sufficient to convert from about 0.5 to about 10.0 percent of the silver halide to silver iodide. It was found also that iodide could advantageously be added to the developer. Such advantages were attained Where a soluble iodide such as potassium, sodium or lithium iodide was added to the developer in the range from about 0.01 to about 0.3 gram per liter of developer.

While any of the well-known alkylene oxide polymers used to sensitize photographic emulsion can be used in practicing this invention the best results are obtained with polymers derived from alkylene oxides composed of from 2 to 4 carbon atoms, e.g., ethylene oxide, propylene oxide and butylene oxide. The preparation of polymers from these compounds is described in Ellis, The Chemistry of Synthetic Resins (1935), pages 990 to 994. The cornpounds embodying the invention are also referred to sometimes as polyalkylene glycols and their use as sensitizers for silver halide emulsions is described in U.S. Patents 2,423,549 and 2,441,389.

Various derivatives of alkylene oxides can also be used in accordance with this invention, e.g., condensation products of alkylene oxide with organic compounds containing an active hydrogen atom. Examples of active hydrogen organic compounds, i.e., compounds in which a hydrogen atom may be -replaced by reaction of the compound Vwith metallic sodium, methylmagnesium iodide, etc., include alcohols, amines, mercaptans, acids, amides, hydrocarbons such as acetylene, and compounds having the active hydrogen in a methylene group such as dibenzoylmethane. More specifically, we may employ condensation products of alkylene oxide with glycols such as those having from 8 to 18 carbon atoms as described in U.S. Patent 2,240,472 and British Patent 443,559 as well 'ory of the Photographic Process, 1942, page 3).

vwith gelatino-silver bromoiodide emulsion.

as condensation products of alkylene oxides with aliphatic alcohols, condensation products of alkylene oxides with aliphatic acids, e.g., lauric acid and glycine, condensation products of alkylene oxides with aliphatic amines or amides, eg., glycine and lauryl amide, and condensation products of alkylene oxides with phenols, e.g., phenol. The preparation of these condensation products is described in U.S. Patent 1,970,578. Condensation products of alkylene oxides with hexitol ring dehydration products as described in U.S. Patent 2,400,532 can also be employed.

, In each case the polyalkylene oxide or derivative of alkylene oxide should have a molecular weight of at least 300. Condensation products of ethylene oxide with long chain alcohols, acids, amines or amides should have a molecular weight of about 700. In general the best results are obtained with the condensation products of ethylene oxide with organic compounds having an active hydrogen and with ethylene oxide polymers having a molecular Weight of 1000 to 3500 or more.

The emulsions can also be optically sensitized with cyanine and merocyanine dyes, such as those described in Brooker U.S. Patents 1,846,301, issued February 23, 1932; 1,846,302, issued February 23, 1932; and 1,942,854, issued January 9, 1934; White U.S. Patent 1,990,507, issued February 12, 1935; Brooker and White U.S. Patents 2,112,140, issued March 22, 1938; 2,165,338, issued July 11, 1939; 2,493,747, issued January 10, 1950, and 2,739,964, issued March 27, 1956; Brooker and Keyes U.S. Patent 2,493,748, issued January 10, 1950; Sprague U.S. Patents 2,503,776, issued April 11, 1950, and 2,519,001, issued August 15, 1950; Heseltine and Brooker U.S. Patent 2,666,761, issued January 19, 1954; Heseltine U.S. Patent 2,734,900, issued February 14, 1956; Van Lare U.S. Patent 2,739,149, issued March 20, 1956; and Kodak Limited British Patent 450,958, accepted July 15, 1936.

When employing optically sensitized emulsions, the optical sensitizing dyes are advantageously employed in about their usual optimum concentration although concentrations above or below the optimum concentration can be employed.

The alkylene oxide derivatives used to sensitize the emulsions may be illustrated by the following specic examples, although out invention is in no way limited to the use of these specic compounds.

HocH2CH2o (CHZCHZO) nCHZCHZOH Polyethylene glycol (CH2) io O (CHzCHzO) nCHzCHzOH Di (polyethylene-glycoxy) -decane HOCH2CH2O (CH2CH2O CH2CH2OC18H35 Polyethylene oxide oleyl ether where n=an integer greater than about 10.

The preparation of silver halide emulsions as used in this invention involves three separate operations: (1) the emulsification and digestion or ripening of the silver halide, (2) the freeing of the emulsion from aqueous soluble salts usually by washing, (3) the second digestion or afterripening to obtain increased sensitivity (Mees, The The- The sensitizing agents embodying this invention are preferably added after the iinal digestion.

The photographic emulsions which we use are of the developing-out type and best results have been obtained However, emulsions of varying halide content such as silver chloride or silver bromide emulsions can be used to obtain optimum results Where iodide is incorporated in the developer.

The emulsions may be chemically sensitized by any of the accepted procedures in addition to or in combination with the colloidal silver incorporated emulsion system sensitized with alkylene oxide polymers. The emulsions may be digested with naturally active gelatin, or sulfur compounds may be added such as those described in Sheppard U.S. Patents 1,574,944 and 1,623,499, and Sheppard and Brigham U.S. Patent 2,410,689.

The emulsions may also be treated with salts of the noble metals such as ruthenium, rhodium, palladium, iridium, and platinum all of Which belong to group VIII of the periodic table of elements and have an atomic weight greater than 100. Representative compounds are ammonium chloropalladate, potassium chloroplatinate and sodium chloropalladite, which are used for sensitizing in amounts below that which produces any substantial fog inhibition, as described in Smith and Trivelli U.S. Patent 2,448,060, and as anti-foggants in higher amounts, as described in Trivelli and Smith U.S. Patents 2,566,245 and 2,566,263.

The emulsions may also be chemically sensitized with gold salts as described in Waller and Dodd U.S. Patent 2,399,083, or stabilized with gold salts as described in Damschroder U.S. Patent 2,597,856 and Yutzy and Leermakers U.S. Patent 2,597,915. Suitable compounds are potassium chloroaurite, potassium aurithiocyanate, potassium chloroaurate, auric trichloride, and 2-aurosulfo- -benzothiazole methochloride.

The emulsions `may also be chemically sensitized with reducing agents such as stannous salts (Carroll U.S. Patent 2,487,850), polyamines such as diethylene triamine (Lowe and J ones U.S. Patent 2,518,698), polyamines such as spermine (Lowe and Allen U.S. Patent 2,521,925), or bis--aminoethyl) sulde and its water soluble salts (Lowe and Jones U.S. Patent 2,521,926).

The emulsions may also be stabilized with the mercury compounds of Allen, Byers, and Murray U.S. application Serial No. 319,611, Carroll and Murray U.S. application Serial No. 319,612 and Leubner and Murray U.S. application Serial No. 319,613, all led November 8, 1952, now U.S. Patents 2,728,663; 2,728,664 and 2,728,665 respectively, granted December 27, 1955.

The emulsions may contain a suitable gelatin plasticizer such as glycerin; a dihydroXy alkane such as 1,5-pentane diol as described in Milton and Murray U.S. application Serial No. 588,951, filed June 4, 1956; an ester of an ethylene bis-glycolic acid such as ethylene bis(methyl glycolate) as described in Milton U.S. application Serial No. 622,564, iiled May 31, 1957; bis-(ethoxy diethylene glycol) succinate as described in Gray U.S. application Serial No. 604,333, tiled August 16, 1956, or a polymeric hydrosol as results from the emulsion polymerization of a mixture of an amide of an acid of the acrylic acid series, an acrylic acid ester and a styrene-type compound as described in Tong U.S. Patent 2,852,386, issued September 16, 1958. The plasticizer may be added to the emulsion before or after the addition of a sensitizing dye, if used.

The emulsions may be hardened with any suitable hardener for gelatin such as formaldehyde; a halogensubstituted aliphatic acid such as mucobromic acid as described in White U.S. Patent 2,080,019, issued May ll, 1937; a compound having a plurality of acid anhydride groups such as 7,8-diphenylbicyclo (2,2,2)7octene 2,3,5,6tetracarboxylic dianhydride, or a dicarboxylic or a disulfonic acid chloride such as terephthaloyl chloride or naphthalene-1,5-disulfonyl chloride as described in Allen and Carroll U.S. Patents 2,725,294, and 2,725,295, both issued November 29, 1955; a cyclic 1,2-diketone such as cyclopentane-1,2dione as described in Allen and Byers U.S. Patent 2,725,305, issued November 29, 1955; a bisester of methanesulfonic acid such as 1,2-di-(methanesulfonoxy)ethane as described in Allen and Laakso U.S. Patent 2,726,162, issued December 6, 1955; 1,3-dihydroxymethylbenzimidazol-2-one as described in July, Knott and Pollak U.S. Patent 2,732,316, issued January 24, 1956; a dialdehyde or a sodium bsulte derivative thereof, the aldehyde groups of Which are separated by 2-3 carbon atoms, such as -methyl glutaraldehyde bissodium bisuliite as described in Allen and Burness U.S. patent application Serial No. 556,031, filed December 29, 1955; a bis-aziridine carboxamide such as trimethylene bis( l-aziridine carboxamide) as described in Allen and Webster U.S. patent application Serial No. 599,891, filed July 25, 1956; or 2,3-dihydroxy dioxane as described in Jeffreys U.S. Patent 2,870,013, issued January 20, 1959.

T he emulsions may contain a coating aid such as saponin; a lauryl or oleyl monoether of polyethylene glycol as described in Knox and Davis U.S. Patent 2,831,766, issued April 22, 1958; a salt of a sulfated and alkylated polyethylene glycol ether as described in Knox and Davis U.S. Patent 2,719,087, issued September 27, 1955; an acylated alkyl taurine such as the sodium salt of N-oleoyl- N-methyl taurine as described in Knox, Twardokus and Davis U.S. Patent 2,739,891, issued March 27, 1956; the reaction product of a dianhydride of tetracarboxybutane with an alcohol or an aliphatic amine containing from 8 to 18 carbon atoms which is treated with a base, for example, the sodium salt of the monoester of tetracarboxybutane as described in Knox, Stenberg and Wilson U.S. Patent 2,843,487, issued July 15, 1958; a water-soluble maleopimarate or a mixture of a water-soluble rnaleopimarate and a substituted glutamate salt as described in Knox and Fowler U.S. Patent 2,823,123, issued February l1, 1958; an alkali metal salt of a substituted amino acid such as disodium N-(carbo-p-tert. octylphenoxypentaethoxy)glutamate as described in Knox and Wilson U.S. patent application Serial No. 600,679, tiled Iuly 30, 1956; or a sulfosuccinamate such as tetrasodium N-(1,2-dicar boxyethyl)-N-actadecyl sulfosuccinamate or N-lauryl disodium sulfosuccinamate as described in Knox and Stenberg U.S. patent application Serial No. 691,125, filed October 2l, 1957, or a sodium salt of an alkylarylpolyether sulfonate of Baldsiefen U.S. Patent 2,600,831, granted .Tune 17, 1952.

Improvements secured by our invention will be more readily apparent by reference to the accompanying drawings which show typical sensitometric curves of exposed and developed photographic material wherein density is plotted against the time of development in a surface developer of the following composition:

Sodium carbonate monohydrate 55.6 Water to make 1 liter.

Curve A of FIGURE l shows the increase in speed obtained where colloidal silver in combination with a polyethylene oxide polymer is added to a standard bromoiodide emulsion. It can be noted that the speed is substantially increased where this combination is used when compared to the speed of emulsions containing only polyethylene oxide polymer (curve B) or colloidal silver (curve D). It can also be noted that the addition of colloidal silver only to the emulsion (curve D) tends to decrease the speed of that emulsion by a marked degree from the speed of an emulsion containing no additive (curve C). The synergistic effect which occurs upon the addition of colloidal silver in combination with `a polyethylene oxide polymer (curve A), is even more evident upon prolonged development. Curve A in FIGURE 2 shows the increase in contrast `obtained when colloidal silver is added to a bromoiodide emulsion in combination with polyethylene oxide. Curve C in FIGURE 2 shows 'the contrast of the untreated bromoiodide emulsion. By

reference to curve C of FIGURE 2 it can be noted that the use of the combination of this invention results in a substantially greater contrast than does the use of either the polyethylene oxide (curve D) or the colloidal silver (curve B) singly. The synergistic effect noted in relationship to speed in FIGURE 1 is seen also to occur with regard to contrast (FIGURE 2) where the combination of colloidal silver and polyethylene oxide polymer is added to a bromoiodide emulsion.

The colloidal silver used in the examples shown in FIGURES l and 2 and in the examples which follow was prepared by the dextrin reduction method of preparation by Carey-Lea as described in Colloidal Elements by Weiser, lohn Wiley and Sons, New York, New York, 1933, page 119.

The following examples further illustrate the sensitizing results obtained in emulsions embodying this invention.

Example I To samples of a gelatin-silver bromoiodide emulsion which had been digested with a sulfur compound such as disclosed in Sheppard U.S. Patent 1,574,944, e.g., allyl thiourea, and a gold compound, elg. auric trichloride were added the compounds as shown in the following sample series. The emulsions were coated on a cellulose acetate support in lthe conventional manner. The coatings were exposed on an Eastman Type IB Sensitometer and processed for 4 minutes at 68 F. in Kodak D-19 Developer of the following composition:

' TABLE II Kodak Developer D-l9: Grams Monomethyl-p-aminophenol sulfate 2.2 Hydroquinone 8.8 Sodium sulte-desiccated 96 Sodium carbonate-desiccated 48 Potassium bromide 5 Water to l liter.

Grams Sample No. Compound per Speed Contrast Fog mole AgX 132 1.18 .15 g1g 170 1. 45 .1s 5'. 0 24o 1. s2 .16

This example demonstrates the supersensitizing eifect in a bromoiodide emulsion of the combination of the polyethylene oxide polymer with the colloidal silver. Samples 6, 7 and 8 show the significant increases in contrast which were obtained together with speed gains Where the combination of this invention was employed. Only small increases in fog resulted, that is, from 0.07 in the control to 0.16 in the most highly sensitized samples even in the absence of an antifogging agent.

Example II Coatings were prepared as described in Example I except that the emulsion contained the following addenda and, in addition, the emulsion used to prepare samples 11 and 12 was green sensitized. Development was for 4 minutes at 68 F. in Kodak Developer D-l9.

Y This ,example shows that the combination of this invention can be used to further enhance the effective speed and gamma of an optically sensitized bromoiodide emulsion. Any of the optical sensitizing dyes disclosed in the above patents, e.g., Brooker and White U.S. 2,112,140, can be used to sensitize the emulsions used in this invention.

Example III To samples of a chemically unsensitized gelatin silver bromoiodide emulsion were added the compounds as shown in the following sample series. Samples 15 and 16 were also green sensitized. The emulsion contained the following addenda. Development was for 4 minutes at 68 F. in Kodak D-19 Developer.

Grams Sample No. Compound pe" Speed Contrast Fog 1D0 e AgX 100 23 19 1,660 .so .as 380 28 16 }1o, ooo 1. 54 .34

The example clearly illustrates that the synergistic combinations of the invention can be used to advantage in chemically unsensitized emulsions as Well as in emulsions that have been chemically sensitized.

Example IV Coatings were prepared as described in Example I except that the emulsion contained the addenda described in the following sample series. The coatings were exposed on a 1B Sensitometer and processed in the developers given, composition of which is hereinbefore described.

exhibiting improved speed and contrast characteristics, said emulsion having uniformly dispersed therein at least one colloidal material selected from the group consisting of colloidal noble metals, silver sulfide and zinc sulfide and containing an alkylene oxide polymer being selected from the class consisting of (l) polyalkylene glycols, and (2) condensation products of alkylene oxide with organic compounds containing an active hydrogen atom, said alkylene oxide containing from 2 to 4 carbon atoms and said alkylene oxide polymer having a molecular weight of at least 300.

2. A light-sensitive silver halide emulsion capable of exhibiting improved speed and contrast in the presence of iodide, said emulsion having uniformly dispersed therein at least one colloidal material selected from the group consisting of colloidal noble metals, silver sulfide and zinc sulfide, and containing an ethylene oxide polymer selected from the group consisting of (l) polyethylene glycols, and (2) condensation products of ethylene oxide with organic compounds containing an active hydrogen atom, said ethylene oxide polymer having a molecular weight of at least 300.

3. A light-sensitive bromoiodide emulsion capable of exhibiting improved speed and contrast characteristics having uniformly dispersed therin at least one colloidal material selected from the group consisting of silver, gold, platinum, palladium, silver sulfide and zinc sulfide, and said emulsion containing an ethylene oxide polymer, said ethylene oxide polymer being selected from the class consisting of (l) polyethylene glycols, and (2) condensation products of ethylene oxide with organic compounds containing an active hydrogen atom, said ethylene oxide polymer having a molecular weight of at least 300.

4. A light-sensitive optically sensitized silver halide emulsion capable of exhibiting improved speed and contrast characteristics having uniformly dispersed therein at least one colloidal material selected from the group consisting of silver, gold, platinum, palladium, silver sulde and zinc sulfide, and said emulsion containing an ethylene oxide polymer, said ethylene oxide polymer being selected from the class consisting of (l) polyethylene glycols, and (2) condensation products of ethylene oxide with organic compounds containing an active hydrogen atom, said ethylene oxide polymer having a molecular weight of at least 300.

5. A light-sensitive optically sensitized bromoiodide emulsion capable of exhibiting improved speed and contrast in the presence of iodide, said emulsion having uni- Grams Elon-Ascorbic Acid Kodak Dev. D-19 of Sample per Dev. of Table `I--pli 10.2 Table II No. Compound mole AgX.

Speed Contrast Fog Speed Contrast Fog 71 1. 04 11 100 94 08 2. 5 135 74 17 182 85 08 0.5 1. 37 11 69 1. 20 11 POOE 490 3. 66 .23 263 1.15 .2a Colloidal gold---. 1. 8 36 1. 38 36 64 1. 18 26 .22 {gooual gold-" 275 1. 50 .54 aso 1.16 .44

The data can be quickly assessed by noting that the lspeed and contrast values increase readily upon the ad- Vdition of either the colloidal gold or the colloidal silver 'when added in combination with the polyethylene oxide.

These results also illustrate that any of the Well-known developers can be used with comparable eiciency in the practice of this invention.

Although the invention has been described in detail with reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as defined herein- Y-above and asdened in the appended claims.

I claim:

1. A light-sensitive silver halide emulsion capable of being a polyethylene oxide o leyl ether.

7. A light-sensitive bromoiodide emulsion having uniformly dispersed therein colloidal gold and containing an ethylene oxide polymer, said ethylene oxide polymer being a polyethylene oxide oleyl ether.

8. A light-sensitive sulfur -and gold sensitized bromoiodide emulsion having uniformly dispersed therein colloidal silver and containing an ethylene oxide polymer, said ethylene oxide polymer being a polyethylene oxide oleyl ether.

9. The method of producing a photographic image comprising (a) exposing a light-sensitive silver halide emulsion having uniformly dispersed therein (1) at least one colloidal material selected from the group consisting of colloidal noble metals, silver sulfide and Zinc sulfide and (2) an alkylene oxide polymer, said alkylene oxide polymer being selected from the class consisting of (l) polyalkylene glycols, and (2) condensation products of alkylene oxide With organic compounds containing an active hydrogen atom, said alkylene oxide containing from 2 to 4 carbon atoms and said alkylene oxide polymer having a molecular Weight of at least 300; and (b) developing said exposed emulsion in a photographic developer.

l0. A method of producing a photographic image comprising (a) exposing a light-sensitive silver halide emulsion having uniformly dispersed therein at least one colloidal material selected from the group consisting of colloidal noble metals, silver sulfide and Zinc sulfide and containing an ethylene oxide polymer selected from the class consisting of (l) polyethylene glycols, and (2) condensation products of ethylene oxide with organic compounds containing an active hydrogen atom, said ethylene oxide polymer having a molecular Weight of at least 300; and (b) developing said exposed emulsion in a photographic developer containing iodide, said iodide being added to said developer as a soluble iodide selected from the group consisting of potassium, sodium, and lithium.

11. A method of producing a photographic image comprising (a) exposing a light-sensitive bromoiodide emulsion having uniformly dispersed therein at least one colloidal material selected from the group consisting of colloidal noble metals, silver sulfide and zinc sulfide and (a) developing said exposed emulsion in the presence of an ethylene oxide polymer, said ethylene oxide polymer being selected from the class consisting of (l) polyethylene glycols, and (2) condensation products of ethylene oxide with organic compounds containing an active hydrogen atom, said ethylene oxide polymer having a molecular Weight of at least 300.

12. The method of producing a photographic image comprising (a) exposing a light-sensitive bromoiodide emulsion having uniformly dispersed therein at least one colloidal material selected from the group consisting of silver, gold, platinum, palladium, silver sulfide and zinc sulfide, and containing an ethylene oxide polymer selected from the class consisting of (l) polyethylene glycols, and (2) condensation products of ethylene oxide with organic compounds containing an active hydrogen atom, said ethylene oxide polymer having a molecular weight of at least 300; and (b) developing said exposed emulsion in a photographic developer.

13. A method of producing a photographic image cornprising (a) exposing a light-sensitive bromoiodide emulsion containing colloidal silver and an ethylene oxide polymer, said ethylene oxide polymer being polyethylene oxide oleyl ether; and (b) developing said exposed emulsion in a photographic developer.

14. A method of producing a photographic image comprising (a) exposing a light-sensitive bromoiodide emulsion containing colloidal gold and an ethylene oxide polymer, said ethylene oxide polymer being polyethylene oxide oleyl ether; and (b) developing said exposed emulsion in a photographic developer.

15. A method of producing a photographic image comprising (a) exposing a light-sensitive silver halide emulsion containing colloidal silver and an ethylene oxide polymer, said ethylene oxide polymer being polyethylene oxide `oleyl ether; and (b) developing said exposed emulsion in a photographic developing agent containing iodide, said iodide being added to the developer as a soluble iodide selected from the group consisting of potassium, sodium and lithium.

References Cited in the iile of this patent UNITED STATES PATENTS Raasch May 3, 1955 Chechak et al. Aug. 19, 1958 OTHER REFERENCES 

10. A METHOD OF PRODUCING A PHOTOGRAPHIC IMAGE COMPRISING (A) EXPOSING A LIGHT-SENSITIVE SILVER HALIDE EMULSION HAVING UNIFORMLY DISPERSED THEREIN AT LEAST ONE COLLOIDAL MATERIAL SELECTED FROM THE GROUP CONSISTING OF COLLOIDAL NOBLE METALS, SILVER SULFIDE AND ZINC SULFIDE AND CONTAINING AN ETHYLENE OXIDE POLYMER SELECTED FROM THE CLASS CONSISTING OF (1) POLYETHYLENE GLYCOLS, AND (2) CONDENSATION PRODUCTS OF ETHYLENE OXIDE WITH ORGANIC COMPOUNDS CONTAINING AN ACTIVE HYDROGEN ATOM, SAID ETHYLENE OXIDE POLYMER HAVING A MOLECULAR WEIGHT OF AT LEAST 300; AND (B) DEVELOPING SAID EXPOSED EMULSION IN A PHOTOGRAPHIC DEVELOPER CONTAINING IODIDE, SAID IODIDE BEING ADDED TO SAID DEVELOPER AS A SOLUBLE IODIDE SELECTED FROM THE GROUP CONSISTING OF POTASSIUM, SODIUM, AND LITHIUM. 